Open clusters and the galactic disk

TL;DR

This study re-evaluates the role of open clusters in the Milky Way's disk, revealing they contributed about 40% to the stellar population, highlighting their significance in galactic evolution.

Contribution

It provides a comprehensive, homogeneous analysis of open clusters using the ASCC-2.5 survey, including discovery, re-measurement, and derivation of their properties and formation history.

Findings

Open clusters contribute around 40% to the stellar content of the Galactic disk.

Detected 130 previously unknown open clusters.

Derived the cluster initial mass function and formation rate.

Abstract

It is textbook knowledge that open clusters are conspicuous members of the thin disk of our Galaxy, but their role as contributors to the stellar population of the disk was regarded as minor. Starting from a homogenous stellar sky survey, the ASCC-2.5, we revisited the population of open clusters in the solar neighbourhood from scratch. In the course of this enterprise we detected 130 formerly unknown open clusters, constructed volume- and magnitude-limited samples of clusters, re-determined distances, motions, sizes, ages, luminosities and masses of 650 open clusters. We derived the present-day luminosity and mass functions of open clusters (not the stellar mass function in open clusters), the cluster initial mass function CIMF and the formation rate of open clusters. We find that open clusters contributed around 40 percent to the stellar content of the disk during the history of our Galaxy. Hence, open clusters are important building blocks of the Galactic disk.